Skip to main content

Surveys for grassland birds of the Malta Field Office-BLM, including a seven-year study in north Valley County

Item Preview

texts
Surveys for grassland birds of the Malta Field Office-BLM, including a seven-year study in north Valley County


Published 2008
SHOW MORE


"April 2008"-cover date

Appendix A, Global and state rank definitions -- Appendix B, Summary of point-count surveys in northern Blaine and Phillips counties during 2007 -- Appendix C, Predictive distribution models for grassland birds

Includes bibliographical references (p. 24-26)

Grassland-associated birds have exhibited thesteepest population declines of any suite of bird species in North America over the past several decades, primarily due to loss of habitat resulting from conversion of native prairie to agricultural production. To better understand the relationships of prairie vegetation structure with presence and relative abundance of native prairie bird species, fixed-radius point counts were randomly placed across BLM lands in north Valley County in areas with native grassland cover. Our objective was to gather habitat information to help guide management of grasslands for a variety of species, including a suite of grassland birds that are of conservation concern. The project evolved into a multi-year inventory (2001-2007). No other project focused on grassland birds in Montana has gathered consistent data at the same locations for this length of time. More than 75 species of birds were recorded on 1410 point-counts (189 - 207 points each year) in north Valley County. Twenty species were recorded on at least one point count every year, nine of which are Montana Species of Concern (SOC): Long-billed Curlew (Numenius americanus), Sprague?s Pipit (Anthus spragueii), Brewer?s Sparrow (Spizella breweri), Lark Bunting (Calamospiza melanocorys), Grasshopper Sparrow (Ammodramus savannarum), Baird?s Sparrow (Ammodramus bairdii), McCown?s Longspur (Calcarius mccownii), Chestnut-collared Longspur (Calcarius ornatus), and Bobolink (Dolichonyx oryzivorous). Chestnut-collared Longspur occurred on the greatest percentage (79.7-89.9%) of our point counts. Next in order of relative abundance were Horned Lark, Western Meadowlark, Sprague?s Pipit, and Baird?s Sparrow. Each of these species was detected every year on at least 30% of our count points. The results of our seven-year study revealed considerable variation in precipitation and vegetation conditions in north Valley County that influenced where birds settled during the breeding season. For the seven years combined, Long-billed Curlew and McCown?s Longspur occupied sites with shorter and less dense grasslands, while Grasshopper Sparrow, Baird?s Sparrow, and Bobolink favored taller and denser grassland patches. Chestnut-collared Longspur and Sprague?s Pipit occupied points with intermediate vegetation height and density near-the ground. Lark Bunting tended to occur on sites where vegetation was moderately taller but of equally low near-ground density as Long-billed Curlew and McCown?s Longspur. Brewer?s Sparrow was most dissimilar from the other species, occupying points with tall vegetation but relatively low near-ground density. April-May precipitation varied among the seven years nearly five-fold, with extremes in 2002 and 2007, respectively, and mean vegetation height and density tended to correspond accordingly. April-May precipitation accounted for 77% of variation in mean vegetation height among years on our points. Likewise, we found April and May precipitation a good predictor of the percentage of point counts on which some SOC birds would occur. Greater numbers of Baird?s Sparrow, Chestnut-collared Longspur, and Bobolink tended to occur in years with greater spring precipitation, while Long-billed Curlew showed a negative response to increased spring precipitation, an expected pattern because this species selects sites with low-stature grass for nesting. Within-year differences in vegetation structure between occupied and unoccupied points were not consistently strong across years for any species except Baird?s Sparrow, which occupied points with taller and denser near-ground vegetation than was available where it was absent. Grasshopper Sparrow occupied points each year with taller or denser vegetation, but not always both. Each of the other SOC birds occupied points in some years that did not differ from unoccupied points in either measure of vegetation structure. That all of these bird species co-occurred every year, sometimes in substantial numbers and despite large differences in preferred vegetation structure, indicates that current management is maintaining a mosaic of vegetation conditions at large enough landscape scales to retain what appears to be a complete or nearly complete mixed-grass prairie bird community. Surveys conducted during 2007 in nearby northern Blaine and Phillips counties found the same SOC birds in roughly the same proportions, with the exception of Baird?s Sparrow, which was less abundant, and McCown?s Longspur, which was more abundant (reflecting shorter and less-dense vegetation in Blaine and Phillips counties). This suggests that a large region of north-central Montana continues to support a diverse grassland bird community. To better understand the extent of this community, which has not been well surveyed, we developed predicted distribution models for 11 grassland SOC birds which should help focus surveys. Outputs from these models highlight the importance of Valley, Phillips, and Blaine Counties to the conservation of these grassland bird Species of Concern in Montana

North-central Montana

Agreement Number


Volume 2008
Publisher Helena, Mont. : Montana Natural Heritage Program
Pages 113
Language English
Book contributor Montana State Library
Contributor usage rights See terms
Collection MontanaStateLibrary; americana

Full catalog record MARCXML

comment
Reviews

There are no reviews yet. Be the first one to write a review.
SIMILAR ITEMS (based on metadata)
Montana State Library
by Hendricks, Paul,1951-; Lenard, Susan; Currier, Coburn,1970-; Carlson, John; Montana Natural Heritage Program
texts
eye 150
favorite 0
comment 0
Montana State Library
by Hendricks, P.(Paul); Currier, Coburn,1970-; Carlson, John C; Montana Natural Heritage Program; United States.Bureau of Land Management.Billings Field Office
texts
eye 538
favorite 0
comment 0
Montana State Library
by Lenard, Susan; Montana Natural Heritage Program; Montana.Dept. of Fish, Wildlife, and Parks
texts
eye 456
favorite 0
comment 0
Bureau of Land Management Library
by Carlson, Barbara A; United States. Bureau of Land Management. California Desert District
texts
eye 165
favorite 0
comment 0
Montana State Library
by Hendricks, P.(Paul); Roedel, Michael; Montana Natural Heritage Program; U.S. Fish and Wildlife Service; United States.Bureau of Land Management
texts
eye 536
favorite 0
comment 0
Internet Archive Books
by Shuford, W. David, 1949-; Point Reyes Bird Observatory
texts
eye 2,109
favorite 1
comment 0
Montana State Library
by Hendricks, P.(Paul); Feigley, Pete; United States.Forest Service; Montana Natural Heritage Program
texts
eye 490
favorite 0
comment 0
Montana State Library
by Hendricks, Paul; Kudray, Gregory M; Lenard, Susan; Maxell, Bryce; Montana Natural Heritage Program
texts
eye 507
favorite 0
comment 0
Montana State Library
texts
eye 555
favorite 0
comment 0
Montana State Library
by Hendricks, P.(Paul); Maxell, Bryce; Lenard, Susan; Currier, Coburn,1970-; Johnson, Joseph; Montana Natural Heritage Program
texts
eye 416
favorite 0
comment 0